Production and mechanical characterization of Titanium Carbide ISOL target disks fabricated by direct ink writing

Titanium carbide boasts a large variety of high-temperature applications from aerospace to electronics and is also employed as Isotope Separation On-Line target for the production of Radioactive Ion Beams, which are employed in numerous research and technological fields, ranging from nuclear physics to medical applications. High working temperature, open and tailored porosity and resistance to thermal stresses are fundamental characteristics for this kind of targets. In this work, an extrusion-based additive manufacturing technique (Direct Ink Writing) was used for the fabrication of complex three-dimensional macro-porous structures in the shape of disks with dimensions compatible for their use as targets. An ink containing a suspension of TiC powders with solid loading of 47.5 vol% was prepared and its rheological properties were investigated. Afterwards, single filaments with an average diameter of 0.36 mm were produced and characterized with four-point bending tests to determine the bulk material tensile strength and Young's modulus. TiC targets were then manufactured and their mechanical properties were characterized with the Ball on Three Balls approach, a biaxial flexural test suitable for disk-shaped samples. For both flexural tests, a Finite Element model was developed representatively reproducing the experimental results. The calculated tensile strength values for both filaments and disks were analyzed with Weibull's statistical approach to provide reference stress limit, corresponding to a survival probability of 99.9%.